Risk Factors for Preterm Birth

Rather than having one cause, preterm birth seems to be triggered by multiple, interacting biologic and environmental factors. We do know that a history of preterm birth, multiple gestations, and certain uterine and/or cervical problems are the strongest risk factors for preterm birth. The factors below also contribute to preterm birth.

Multiple births

In Missouri in 2015, 7.9% of singleton births were preterm, compared to 65.9% of multiple births. Multiple births represent 3.7% of live births in Missouri. Current multifetal pregnancy is one of the most consistently identified risk factors for preterm birth.

Birth spacing

Birth spacing, or inter-pregnancy interval, is the timing between a live birth and the beginning of the next pregnancy. Birth spacing of less than 18 months increases the risk of preterm birth and other adverse outcomes. In the United States, 33.1% of pregnancies with a prior live birth have a birth spacing of less than 18 months.

Obesity

While obesity does not directly cause preterm birth, it does increase rates of medical complications (e.g., hypertension, diabetes) that contribute to preterm birth. In Missouri, 29.5% of women of childbearing age were obese in 2016.

Health insurance coverage

In 2016, about 1 in 8 women of childbearing age (13.2%) was uninsured in Missouri. Health care before, during and after pregnancy can help identify and manage conditions that contribute to preterm birth.

Other contributing factors

Other factors contributing to preterm birth include: infection (especially genito-urinary), diabetes mellitus, hypertension, late or no prenatal care, alcohol and illicit drug use, and social determinants of health. Socioeconomic status at both the individual and community level (e.g., income/poverty, job status, education) as well as psychosocial factors (e.g., chronic stress, lack of social support) are associated with an increased risk of preterm birth.

Consequences of Preterm Birth

Prematurity is the leading cause of newborn death and disability among infants, including developmental delays, chronic respiratory problems, and vision and hearing impairment. In addition to the health consequences of preterm birth, the emotional and economic impact of preterm birth on families is too high.

In Missouri in 2013, the infant mortality rate due to prematurity/low birthweight was 127.5 per 100,000 live births, which accounts for 19.5% (491) of all infant deaths.

Preterm-related and other leading causes of infant deaths, United States, 2013

36.3%

When causes of death related to preterm birth are grouped together, preterm-related causes account for more than one third (36.3%) of infant deaths in the United States. (See figure.)

$26.2B

Associated with preterm birth

In 2005, the annual societal economic cost (medical, educational, and lost productivity) associated with preterm birth in the United States was at least $26.2 billion.

March of Dimes National Prematurity Campaign

The Mission of the March of Dimes is to improve the health of babies by preventing birth defects, preterm birth, and infant mortality. Prematurity is the leading cause of newborn death and a major determinant of illness and disability among infants. The March of Dimes leads the national Prematurity Campaign, with the goal of achieving equity and demonstrated improvements in preterm birth. For more information, visit marchofdimes.org/prematurity